Burglar alarm



Feb. 1, 1955 c. R. BERRY 2,701,282

BURGLAR ALARM Filed June 25, 1951 United States Patent O BURGLAR ALARMCleveland R. Berry, Conway, Ark.

Application June 25, 1951, Serial No. 233,431

1 Claim. (Cl. 200-61.83)

The present invention relates to burglar alarms and more particularly isconcerned with an alarm which is set off upon the opening of a doorafter the alarm has been set.

The principal object of the present invention is to provide a verysimply operated and economical alarm which will operate upon the openingof a d-oor to which the alarm is connected.

A further and important object of the invention is to provide an alarmto be operated by the opening of a door and which alarm can be connectedto or detached from the door as desired.

Further objects of the invention will be in part obvious and in partpointed out in the following detailed description of the accompanyingdrawings wherein,

Fig. 1 is a side elevation of a door and a wall with the present burglaralarm connected thereto and set for enunciating unwarranted entrancesthrough the door;

Fig. 2 is a horizontal section taken on line 2--2 of Fig. 1;

Fig. 3 is a horizontal section with the present alarm mounted on thehinged side of the door just prior to setting off the alarm;

Fig. 4 is a front elevation of the burglar alarm with the front of theelectric switch removed showing the interior thereof at the time thealarm is put into operation;

Fig. 5 is an enlarged side elevation of the thread cutter block taken online 5-5 of Fig. 1.

Referring now more in detail to the drawing, wherein like andcorresponding parts are indicated by similar reference characters,numeral 1 indicates a door pivotally supported by hinges 2 to a jamb 3fastened to a wall 4. Numeral 5 refers to an eye screwed into the doorand thus tlxedly attached thereto.

One arrangement of the burglar alarm as shown on the drawings consistsof a base plate fastened to the wall 4 by screws 11.

A switch box 12 having a longitudinal slot 13 formed in one side thereofand an opening 14 through its top is fastened to said plate 10 by screws15. Within this box there is slidably positioned a metallic ball 16having an eye 17 extending from the top thereof and an electricalconductive wire 18 connected to a side of said ball and extendingtherefrom through said slot 13. In the bottom of the interior of saidbox there is flatly positioned a metallic perforated disc 19 from whichextends an electrical wire 20. Said ball 16 and disc 19 are formed fromelectrically conductive metal such as copper.

Said wire 20 extends to one connector of an electric bell 21, while theother connector of said bell is connected by a wire 22 to one connectorof a battery 23. Said wire 18 is connected to the other connector ofsaid battery 23.

A thread or string 25 is connected to eye 17 of ball 16 and extendsthrough opening 14 of said box vertically to and through an eye 26mounted on said plate 10 directly above said opening 14. Said string 25then extends substantially at a right angle to a block 27. Said block 27contains a cutting element such as a razor blade 28 which is retainedtherein by staples 29. Said block 27 is in turn fastened to plate 10 byscrews 30 and has an opening 31 formed therethrough into which extendsthe cutting edge 2,701,282 Patented Feb. 1, 1955 ICC of said blade 28.String 25 extends through said opening 31 to eye 32 to which it isattached to the hook 33. Eye 26, opening 31 and eye 5 are thus insubstantially a straight line whereupon the string 25 is held taut insaid straight line when hook 33 is fastened to eye 5 due to the weightof ball 16. Block 27 is sized for holding 'blade 28 out of contact withstring 25 when it is taut until such time as the door is opened.

When it is desired to permit the free use of the door 1 without settingoff the alarm, hook 33 can be detached from eye 5 and wire 18 detachedfrom the battery 23 either manually or by means of a switch. However atsuch times as it becomes desirable to have the bell 21 indicate theunwarranted opening of said door 1, then hook 33 is fastened to eye 5and the circuit positioned as shown in Figs. 1 and 2 of the drawings.When the door is opened by an intruder as indicated in Fig. 3, string 25being held taut is caused to bear upon cutting edge of blade 28 whichsevers said string and as shown in Fig. 4 the string then slides overeye 26 and through opening 14 causing ball 16 to drop by gravity untilit contacts the perforated disc 19. The perforations in said disc 19provide a plurality of faces for being contacted by said ball 16 thusassuring a good electrical connection therebetween and the circuitbetween batteries 23 and bell 21 is thus closed causing the bell toenunciate and give a warning of the entrance of a possible burglar.

As can be noted, the alarm can be mounted on the latch side of the door,as shown in Figs. 1 and 2 or on the hinge side of the door as shown inFig. 3. The operation of the alarm is substantially the same in eitherinstance.

When it is desired to unhook the alarm from the door by removing hook 33from eye 5, the hook 33 can then be attached to eye 35 whereupon ball 16will be prevented from dropping and setting orf the bell.

The present invention is capable of considerable modilication and suchchanges thereto which come within the scope of the appended claims aredeemed to be a part of the invention.

iIclaim:

A door operated `electrical circuit closing device comprising incombination with a hinged door, a vertically positioned support, astring, means for detachably connecting an end of said string to theopening side of said door, a weight attached to the opposite end of saidstring, means mounted on said support slidably supporting a portion ofsaid string on a horizontal line with said connecting means with theremainder of said string extending vertically with said weight at thelower end thereof, a block xedly positioned on said support between andon a horizontal line with said detachable means and said supportingmeans, said block having an opening provided therethrough with saidhorizontal portion of said string freely extending through said opening,a cutting member supported by said block and extending into saidopening, but normally out of contact with said string therein until saiddoor is pivoted open whereby said string is drawn across said cuttingmember and cut thereby, an electrical circuit, and switch means for saidcircuit positioned for being closed by said weight upon its downwardmovement at the cutting of said string.

References Cited in the le of this patent UNITED STATES PATENTS 761,572Barger May 31, 1904 886,355 Dawson May 5, 1908 1,099,777 Sundel June 9,1914 1,107,945 Hesse Aug. 18, 1914 1,252,196 Taylor et al. Jan. 1, 1918FOREIGN PATENTS 20,678 Great Britain Nov. 27, 1891 5,562 Great BritainMar. 16, 1901

